1. Field of the Invention
The present invention relates to a microlens and its forming method being suitably used in devices for optical communications and more particularly to the microlens and its forming method being suitably applied to formation of many very fine and small diffractive optical elements such as computer-generated hologram (CGH) devices.
2. Description of the Related Art
A method for forming many microlenses each being coupled to an optical fiber is disclosed in “Proceeding SPIE (Vol. 3631, p234-243)” issued in April 1999. According to this conventional technology, by tying many cylindrical optical elements each having an outer diameter equal to that of an optical fiber in a bundle and by performing etching processing on end faces of the optical elements using specified etching mask, many specified lens planes can be formed on an end face of each of the many optical elements in a collective manner.
By using the microlens made from such the optical element having the same outer diameter as that of the optical fiber, when the microlens is placed in a V-groove on a substrate in a manner that an end face of a lens plane faces an end of the optical fiber being also placed in the V-groove, it is possible to accurately align an optical axis of the microlens with that of the optical fiber.
However, the conventional method for forming the microlens described above has problems. That is, in the conventional method, in order to collectively form the lens plane on end faces of many optical elements, it is necessary to surely and accurately tie many optical elements in a bundle, however, it is not easy to accurately tie many optical elements in a bundle and to reliably form the lens plane on the end faces of the many optical elements.